Cellulosic fibrous webs such as paper are well known in the art. Low density fibrous webs are in common use today for paper towels, toilet tissue, facial tissue, napkins, wet wipes, and the like. The large demand for such paper products has created a demand for improved versions of the products and the methods of their manufacture. In order to meet such demands, papermaking manufacturers must balance the costs of machinery and resources with the total cost of delivering the products to the consumer.
For conventional papermaking operations, wood cellulosic fibers are re-pulped, beaten or refined to achieve a level of fiber hydration in order to form an aqueous pulp slurry. Processes for the making of paper products for use in tissue, toweling, and sanitary products generally involve the preparation of the aqueous slurry and then subsequently removing the water from the slurry while contemporaneously rearranging the fibers therein to form a paper web. Subsequent to dewatering, the web is processed into a dry roll or sheet form and eventually converted into a consumer package. Various types of machinery must be employed to assist in the dewatering process and converting operations requiring a significant investment in capital.
Another aspect of the conventional papermaking operation involves the incorporation of additives into the pulp in order to achieve specific end properties. For instance, additives such as strength resins, debonding surfactants, softening agents, pigments, lattices, synthetic micro-spheres, fire-retardants, dyes, perfumes, etc., are often employed in the manufacture of paper. The efficient retention of these additives at the wet end of a papermaking process presents difficulty to the manufacturer since that portion which is not retained creates not only an economic loss but also significant pollution problems if it becomes part of a plant effluent. Additives can also be added to the paper web subsequent to dewatering via coating or saturation processes commonly known in the art. These processes usually require that excess heating energy be consumed to re-dry the paper after coating. Moreover, in some instances, the coating systems are required to be solvent based which increases capital costs and requires recovery of volatile materials to meet regulatory requirements.
Various natural fibers other than cellulose as well as a variety of synthetic fibers have been employed in making paper, however, all these replacements have failed to provide a commercially acceptable substitute for cellulose due to their high cost, poor bonding properties, chemical incompatibilities, and handling difficulties in manufacturing systems. Starch filaments have been suggested as a substitute for cellulose in various aspects of the papermaking process, however, commercial attempts to use such starch filaments have been unsuccessful. As a result, paper products are still being manufactured almost exclusively from wood-based cellulosic ingredients.
Accordingly, the present invention provides a flexible structure comprising long starch filaments and a process for making same. Particularly, the present invention provides a flexible structure comprising a plurality of starch filaments, wherein the structure comprises two or more regions having distinct intensive properties for improved strength, absorbency, and softness.
The present invention also provides methods of making starch filaments. Particularly, the present invention provides an electro-spinning process of producing a plurality of starch filaments.